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参数资料
| 型号： | LTC3890IUH#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | DUAL SWITCHING CONTROLLER, 585 kHz SWITCHING FREQ-MAX, PQCC32 |
| 封装： | 5 X 5 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, MO-220WHHD, QFN-32 |
| 文件页数： | 13/38页 |
| 文件大小： | 381K |
| 代理商： | LTC3890IUH#TRPBF |
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LTC3890
20
3890fa
APPLICATIONS INFORMATION
Tracking and Soft-Start (TRACK/SS Pins)
The start-up of each VOUT is controlled by the voltage on
the respective TRACK/SS pin. When the voltage on the
TRACK/SS pin is less than the internal 0.8V reference,
the LTC3890 regulates the VFB pin voltage to the voltage
on the TRACK/SS pin instead of 0.8V. The TRACK/SS pin
can be used to program an external soft-start function
or to allow VOUT to track another supply during start-up.
Soft-start is enabled by simply connecting a capacitor
from the TRACK/SS pin to ground, as shown in Figure 6.
An internal 1μA current source charges the capacitor,
providing a linear ramping voltage at the TRACK/SS pin.
The LTC3890 will regulate the VFB pin (and hence VOUT)
according to the voltage on the TRACK/SS pin, allowing
VOUT to rise smoothly from 0V to its final regulated value.
The total soft-start time will be approximately:
tSS = CSS
0.8V
1μA
TIME
VX(MASTER)
VOUT(SLAVE)
OUTPUT
VOLTAGE
3890 F07a
TIME
3890 F07b
VX(MASTER)
VOUT(SLAVE)
OUTPUT
VOLTAGE
1/2 LTC3890
VOUT
Vx
VFB
TRACK/SS
3890 F08
RB
RA
RTRACKA
RTRACKB
(7a) Coincident Tracking
(7b) Ratiometric Tracking
Figure 8. Using the TRACK/SS Pin for Tracking
1/2 LTC3890
TRACK/SS
CSS
SGND
3890 F06
Figure 6. Using the TRACK/SS Pin to Program Soft-Start
Alternatively, the TRACK/SS pin can be used to track two
(or more) supplies during start-up, as shown qualitatively
in Figures 7a and 7b. To do this, a resistor divider should
be connected from the master supply (VX) to the TRACK/
SS pin of the slave supply (VOUT), as shown in Figure 8.
During start-up VOUT will track VX according to the ratio
set by the resistor divider:
VX
VOUT
=
RA
RTRACKA
RTRACKA + RTRACKB
RA + RB
For coincident tracking (VOUT = VX during start-up):
RA = RTRACKA
RB = RTRACKB
Figure 7. Two Different Modes of Output Voltage Tracking
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3890HUH#PBF | DUAL SWITCHING CONTROLLER, 585 kHz SWITCHING FREQ-MAX, PQCC32 |
| LTC3890HUH#TRPBF | DUAL SWITCHING CONTROLLER, 585 kHz SWITCHING FREQ-MAX, PQCC32 |
| LTC3891HFE#TRPBF | SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PDSO20 |
| LTC3891HUDC#TRPBF | SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PQCC20 |
| LTC3891MPFE#TRPBF | SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PDSO20 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3890MPGN-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3890MPGN-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3890MPGN-3#PBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM CM 28SSOP 制造商:Linear Technology 功能描述:DC-DC CONTROLLER BUCK 900KHZ 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, BUCK, 900KHZ, SSOP-28 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, BUCK, 900KHZ, SSOP-28; Primary Input Voltage:60V; No. of Outputs:2; No. of Pins:28; Operating Temperature Min:-55C; Operating Temperature Max:150C; Operating Temperature Range:-55C to +150C ;RoHS Compliant: Yes |
| LTC3890MPGN-3#TRPBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM CM 28SSOP |
| LTC3890MPUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
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